How can I add loops cuts to all the parent selection within an object?
Shift+H to hide the everything else while your face loops selected.
Switch to edge selection mode and select one of the short edges
Shift+G to select similar and choose Length from the menu to select all the edge rings.
Hit W and select Subdivide from the menu and in the operator panel or by hitting F6 change number of subdivisions to 2 to make 2 edge loops across all the edge rings.